Solved. I realized i1 was triggering i2 so it was necessary to modify instr 1 from:

schedkwhen  kTrig,0,0,2,0,1

to:

schedkwhen  kTrig,0,0,2,0,1,p4

So instr 1 is then passing p4 to instr 2.

Modifying the line in instr 2, as I had previously done:

aSig  wgpluck2  0.98, 0.2, cpsmidinn(iNote+p4+iDtn), iPlk, 0.06

now works.

May seem basic to some but the exercise of resolving these things really helps me to understand Csound better.

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